The term “cooling cycle” refers to a cycle of a thermodynamic process of absorbing heat from a cold mass and transferring the heat to a thermal mass. The simplest apparatus using such a cooling cycle may include a compressor, a condenser, an expansion device and an evaporator.
The compressor serves to compress a refrigerant and discharge the refrigerant in the form of high-temperature and high-pressure gas, and the condenser serves to condense the high-temperature and high-pressure refrigerant discharged from the compressor into a liquid-phase refrigerant having an intermediate or lower temperature and a high pressure.
The expansion device serves to expand the refrigerant having an intermediate or lower temperature and a high pressure, into a low-temperature and low-pressure refrigerant, and the expanded refrigerant is evaporated in the evaporator. At this time, the temperature and pressure of the refrigerant decreases further. Upon evaporation of the refrigerant, the refrigerant absorbs ambient heat, thus cooling the ambient air.
As the expansion device, a capillary tube or an expansion valve may be used.
The refrigerant, which has been circulated through one cycle, is transferred to the compressor again, and repeatedly undergoes the cyclical process. During this cycle process, the evaporator absorbs ambient heat, whereby cooled air or cold air is generated. The refrigerator transfers the cold air to a cooling compartment by means of a blower, thereby cooling the inside of the cooling compartment.
An increase in the amount of heat of the evaporator in the cooling cycle means increased cooling performance relative to the amount of work done by the compressor (coefficient of performance; COP).
However, heat loss may occur while the refrigerant is expanded in the expansion device, thereby increasing the dryness at the inlet of the evaporator. The evaporator is constructed such that a liquid-phase refrigerant absorbs heat from the ambient air while being evaporated, that is, being vaporized. The increase in the dryness of the evaporator means that an increasing proportion of the refrigerant introduced into the evaporator is gas-phase refrigerant. Here, since the gas-phase refrigerant is not evaporated in the evaporator, there is a problem in that the gas-phase refrigerant is not able to behave as a heat source for the evaporator, thereby decreasing the COP.
Therefore, there is a need to lower the dryness of the refrigerant introduced into the evaporator by separating liquid-phase refrigerant from gas-phase refrigerant in the refrigerant that has passed through the expansion device.
Although the conventional cooling cycle is provided with an accumulator, which is adapted to separate the liquid-phase refrigerant, which has still not evaporated, from the refrigerant that has passed through the evaporator, and to transfer only this gas-phase refrigerant to the compressor, there is a problem whereby the separated liquid-phase refrigerant accumulates in the accumulator and thus cannot be reused.